Electrochemical machining cell



April 14, 1970 I J. M. WENTZELL, I 3,506,557

ELECTROCHEMI CAL MACHINING CELL Filed Feb. 1. 1967 6 Sheets-Sheet 1 April 1970 J. M. WENTZELL 3,506,557

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April 14, 0 J.- M. WEN'TZELL 3,506,557

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AWFOEI EY United States Patent 01 ice 3,506,557 ELECTROCHEMICAL MACHINING CELL Joseph M. Wentzell, Remsen, N.Y. assignor to Allegheny Ludlum Steel Corporation, Brackenridge, Pa., a corporation'of Pennsylvania Filed Feb. 1, 1967, Ser. No. 613,151 Int. Cl. B01k 3/00; C23b /68 US. Cl. 204-206 6 Claims ABSTRACT OF THE DISCLOSURE An electrochemical machining cell having axially aligned entrance and exit ends communicating with a central fluid-tight cavity in which is positioned an annular electrode, the entrance and exit end each having a mating pair of rollers with grooved-out portions about the peripheries thereof, the grooved-out portions mating to form an aperture for the passage of the workpiece therethrough, the aperture having substantially the same configuration as the cross section of the workpiece. The four rollers are synchronized with the speed of the workpiece which travels through the annular electrode, the workpiece itself having the opposite polarity to the annular electrode, and the electrolytic fluid is transmitted into the cavity and about the workpiece to electrochemically machine the surface thereof. Adjusting means and sealing means are provided to cooperate with the rollers to maintain a substantially fluid-tight cavity while the workpiece extends therethrough.

BACKGROUND OF THE INVENTION In electrochemical machining or finishing of elongated rods, it is desirable to subject the entire surface of the rod uniformly to an electrolytic solution. With some rods of the rigid or semi-rigid variety, it is not feasible to subject them to that type of electrolytic solution except in bulk form of short lengths by dipping for a predetermined time. Additionally, prior art electrochemical cells have not been readily adaptable to continuous automatic feed-through of a workpiece of indeterminate length.

It is accordingly an object of this invention to provide new and improved electrochemical machining apparatus.

It is another object of this invention to provide new and improved electrochemical machining apparatus for elongated workpieces.

It is a further object of this invention to provide new and improved electrochemical machining apparatus for workpieces of indeterminate length.

It is still another object of this invention to provide new and improved electrochemical machining apparatus for through-feeding of elongated workpieces without the nec essity of flexing the same.

It is a still further object of this invention to provide new and improved electrochemical machining apparatus having novel sealing means for limiting escape of the electrolyte.

It is an additional object of this invention to provide new and improved electrochemical machining apparatus with provision for assisting movement of the workpiece through the cell.

SUMMARY OF THE INVENTION The foregoing and other objects of the invention are accomplished by providing an electrochemical machining cell having entrance and exit ends with axially aligned apertures for the moving workpiece, each end being provided with a pair of flexible mating sealing rollers. Each of the rollers has thesame general configuration with a grooved-out central portion about the periphery thereof, the conjoined grooves forming an opening of the approximate size and configuration of the workpiece cross section. Means coacting with the sealing rollers are provided to 3,506,557 Patented Apr. 14, 1970 anode, and an annular cathode is provided within the cell concentric to the axis of travel of the workpiece.

BRIEF DESCRIPTIONS OF THE DRAWINGS These and other objects, together with a fuller understanding of the invention, will become apparent from the following description when taken in conjunction with the accompanying drawing in which:

FIGURE 1 is an exploded view of the front portion of the electrochemical machining cell according to the invention;

FIG. 2 is an isometric view of the assembled electrochemical machining cell according to the invention;

FIG. 3 is a side elevational view of the apparatus of FIG. 2 with a portion thereof broken away;

FIG. 4 is a sectional view taken substantially along line IV-IV of FIG. 3;

FIG. 5 is a back side elevational view with portions thereof broken away to show inner construction details; and

FIG. 6 is a plan view of the cell with portions thereof broken away to show inner construction details.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and particularly to FIG. 1, there is shown an exploded view of an electrochemical machining cell generally designated 10. Inasmuch as the cell 10 is symmetrical with respect to a vertical plane through the midpoint thereof, the components for the front end only are illustrated to simplify the drawing and explanation thereof. The cell housing 10 includes an upper H-shaped casting 12 and a lower H-shaped casting 14, the two castings being basically identical in size and configuration and differing only where needs dictate for the purpose of providing flow of the electrolytic solution and providing current for the inner electrode. The casting 12 is provided on each end with a pair of parallel projections or arms 16, and similarly casting 14 is provided with a pair of spaced parallel arms 18. The casting 14 is shown as having a machined-out portion 20 extending along the length thereof. The upper casting 12 has a similar machined-out portion (not'shown), the two portions forming a cavity 22 when the castings 12 and 14 are connected in abutting aligned relationship by means of nuts and bolts 24. The abutting longitudinal surfaces of the two castings are machined to provide a fluid tight seal.

A generally U-shaped upper adjusting block 26 has opposing legs 28 adapted to slidably engage the arms 16 of upper casting 12. Axially aligned apertures 30 are provided in the arms 16 and are adapted to be aligned with axially aligned apertures 32 in the legs 28 of upper adjusting block 26. It is to be noted that apertures 30 are larger in diameter than apertures 32 for purposes which will hereinafter become obvious (see also FIG. 4). An axle 34 has a gear 36 aflixed to one end thereof, the axle 34 being provided with a bushing 38 adapted to be inserted into aperture 32. The axle 34 is inserted through the aligned pairs of apertures 30 and 32 with a roller 40 affixed to the axle 34 and interposed between the arms 16 of upper casting 12. The axle 34 is then suitably secured for rotative movement by means of washer 42 and horseshoe clip 44 engaging the groove 46 adjacent the free end of axle 34. The roller 40 is generally cylindrical and of the same thickness as the space between the arms 16 of upper casting 12. The roller 40 is provided with recessed surfaces 48 on the opposite faces thereof, recessed surfaces 48 acting to reduce friction between the roller 40 and the inner opposed surfaces of the arms 16 during rotation of the roller 40. This will provide a seal as well as reducing the friction. The roller is composed of a flexible yet rigid material such as hard rubber. The roller 40 is provided with a semi-circular groove about the periphery thereof, the groove of the upper roller 40 and the mating lower roller forming a circular opening 52 for passage of a workpiece therethrough. While the opening 52 is shown to be circularly formed, it is to be understood that this opening can take any geometrical shape corresponding to the cross-sectional configuration of the workpiece to be treated. The lower casting 14 is similarly provided with a lower adjusting block 54 which is generally U shaped having axially aligned apertures 56 in the arms 58 thereof. (Se-e also FIG. 4.) The apertures 56 are adapted for the insertion of the bushing 62 and aligned with apertures of arms 18 of lower casting 14. An axle 64 having a gear 66 secured to one end thereof is inserted through bushing 62 and through a central aperture in roller 50, the roller 50 being secured to the axle 64. The gears 36 and 66 mesh for corresponding rotational movement at a 1:1 ratio. The axle 64 is provided with a projecting hub 68 having secured thereto a sprocket 70. A link chain 72 engages the teeth on the sprocket and is coupled to an identical sprocket affixed to the lower axle of the rearward portion of the cell 10. A centrally located aperture 74 is located in the free end of axle 64 through which is inserted a shaft 76 of a torque-assist motor 78, the motor 78 being secured to the arm 58 of lower adjusting block 54 by suitable means such as screws 80. The shaft 76 of motor 78 is aflixed to the aperture 74 of axle 64 by means of a key 81.

Adjusting means are provided in the upper casting 12 A shaft 82 has an eccentric portion 84 and affixed to the eccentric portion 84 is a ratchet wheel 86. The shaft 82 is adapted for insertion through an aperture 88 extending through the upper casting 12 While the eccentric portion 84 rotatively engages a bronze bushing 90 which fits into an aperture 92 located in the legs 28 of upper adjusting block 26. The ratchet wheel 86 is engaged by a pawl 94 which is spring loaded to provide rotation in one direction only. The ratchet wheel 86 has a rectangular hub 96 affixed thereto, the hub 96 being adapted for engagement by a wrench or a key, the purposes of which will become obvious.

Studs 102 secure the upper and lower adjusting blocks by means of aligned apertures therein and apertures extending through the arms 16 and 18 of castings 12 and 14 respectively. A top pressure plate 98 which is essentially T-shaped has a larger portion 100 of the same general dimensions as the bight portion of the upper adjusting r block 26. The portion 100 has four apertures located therein for alignment with studs 102 and nuts 104 are affixed to the threaded end of studs 102 for securing the assembly. A centrally located aperture 105 is provided in the enlarged portion 100 of top pressure plate 98 and a pressure bolt 106 is threadably inserted therein. The leg 108 of the top pressure plate 98 is provided with an aperture through which is inserted a bolt 110 which threadably engages an aperture in the upper casting 12. The upper casting 12 and the lower casting 14 are additionally secured together by means of bar members 112 which are suitably secured to the lower casting 14 by means of screws 114. The upper end of bar member 112 is provided with a slot 116 through which is inserted a bolt 118.

The assembled electrochemical cell shown in FIG. 2 is an isometric view with an elongated workpiece 120 (drawn in transparent form) extending through the cell 10 and being engaged by the rollers 40 and 50. The cell 10 is of the feed-through variety and requires no deformation of the workpiece 120. A pair of electrical contactors 122 are resiliently coupled together by means of a bolt 124 having spring means 126 encircling the bolt 124 for biasing the opposite contactors 122 toward each other.

The contactors 122 have enlarged portions 128 which are shaped according to the configuration of the workpiece 120 to provide continuous contact therewith. Suitable tubing 130 is secured in heat-transferring relationship to the outer surfaces of the contactors 122 for the purpose of providing cooling by water or other fluid flowing therethrough. The contactors 122 are electrically connected to make the workpiece 120 anodic.

The arrangement of the rollers 40 and 50 is shown in detail in FIGS. 4, 5 and 6. As shown in FIG. 4, the rollers 40 and 50 are essentially cylindrical, the semi-circular cutaway portions thereof forming a circular aperture 52 through which the workpiece passes. The rollers 40 and 50 are urged together to eflfect a substantial seal with the workpiece 120 extending therethrough. The means for effecting the relative positioning of the rollers with respect to each other is accomplished by the upper adjusting block 26 and the lower adjusting block 54. The position of the roller 40 with respect to the top adjusting block 26 is fixed, and vertical adjustment with respect to the arms 16 of upper casting 12 is accomplished by means of positioning the upper adjusting block 26 with respect to the upper casting 12. As can be seen in FIG. 4, a space 132 exists between the top surface of the upper casting 12 and the lower surface of the upper adjusting block 26. Similarly, as previously explained, space exists between the axle 34 and the oversized aperture 30. The space 132, and consequently the downward pressure on roller 40, can be 'varied by tightening pressure bolt 106 which urges adjusting block 26 downwardly against the force provided by the top pressure plate 98 which is secured in position by the studs 102 and nuts 104. In order to eliminate unnecessary friction, it is desired that the points of contact of the roller surfaces be in the same plane as the center line of the workpiece. This is accomplished by providing for horizontal adjustment of the rollers 40 and 50 by rotation of the eccentric cam portion 84 about its shaft 82 which will horizontally displace the upper adjusting block 26 with respect to the upper casting 12 to thereby shift the axes of rollers 40 and 50. As can be seen in FIG. 3, horizontal adjustment is provided for each of the four adjusting blocks.

Referring to FIG. 5 there is shown the cavity 22 formed by the cutout portions of upper casting 12 and lower casting 14. An annular electrode 134 is composed of two pieces, each secured to its respective housing by means of a key 136. The electrode 134 serves as a cathode, and the aperture therein is of sufficient size to permit travel of the workpiece 120 therethrough without physical contact. Located in close proximity to and coaxial with cathode 134 is a guide bushing 138 of suitable insulating material (preferably Teflon) which is secured to the housing by means of key member 140. As can be seen the aperture in bushing 138 is smaller in diameter than the aperture in electrode 134 to thereby support the workpiece 120 during its travel in the cell. Located intermediate electrode 134 and bushing 138 is an enlarged groove portion 142, and communicating therewith is an aperture which leads to outlet pipe 144. The electrolyte is injected into the cell through a pipe 146 located generally centrally in the bottom of lower casting 14 through aperture 143 communicating with cavity 22. (See FIG. 3, also.) The electrolyte flows in either direction around the workpiece 120 and is withdrawn through outlet pipes 144. Thus it can be seen that a continual flow of electrolyte is provided. The cathode receives its power from an annular conductor 148 which is concentric to inlet pipe 146, the conductor 148 being wedged into a circular cut-out 149 in the base of lower casting 14 to make castings 12 and 14 cathodic and provide the conduction to electrodes 134. The concentricity of conductor 148 and inlet pipe 146 thus provides cooling of conductor 148 by means of the electrolyte solution.

Inasmuch as the internal construction of the cell 10 is generally symmetrical with respect to a vertical plane therethrough, the second cathode 134, and the second With the workpiece 120 positioned within the cell 10,

the aperture 52 is substantially sealed. In order to prevent the escape of electrolyte around the rollers 40 and 50, rubbing or sealing bars 150 and 152 (FIGS. and 6) having a semi-circular configuration are positioned by means of guide pins 154 on the vertical surfaces of castings 12 and 14 intermediate arms 16 and 18 respectively. The outer surface of sealing bar 150 for example is essentially identical in configuration to the grooved-out portion of roller 40 and engages this grooved-out surface to effect a seal. The horizontal adjustment previously mentioned can be utilized to urge the roll 40 against the sealing bar 150 to maintain this seal. Similarly the groovedout surface of roller 50 can be urged against sealing-bar 152 to effect a lower seal.

In actual operation, workpieces of indeterminate length having uniform cross sections can be fed to the cell from a payoff reel in a continuous automatic fashion with the end of each workpiece being welded to the beginning of another similar workpiece from a second reel. The treated workpiece exiting from the cell can either be rewound on another reel or cut off in desired lengths. Straightening means can also be provided at either the exit end of the cell or the entrance end of the cell, or both if desired. With the workpiece in position with some portion thereof projecting through the exit rollers, the circulation of the electrolyte can be initiated and the current applied. As can be seen in FIGS. 2 and 3 with the gear and sprocket arrangement, the four rollers will rotate at the same speed which is, of course, dictated by the linear speed of the workpiece through the cell. A torque-assist motor 78 is provided to insure substantial correlation between the feed rate of the workpiece and the angular velocity of the rollers. The sealing :of the electrolyte Within the cavity 22 is accomplished by means of the rollers and the sealing bars. It is thereby understood that while there has been shown a workpiece of circular configuration, other elongated workpieces of uniform cross section can be electrochemically machined by this apparatus by making obvious modifications thereto.

What is claimed is:

1. An electrochemical cell for machining an elongated workpiece of uniform cross-section, such as a rod, bar, or the like, comprising: a housing having a longitudinal cavity extending therethrough opening into an entrance end and an exit end adapted for passage of said workpiece therethrough; a first pair of sealing rollers mounted to said housing adjacent said entrance end, the peripheries of said rollers abutting in a plane located centrally of said cavity; a second pair of sealing rollers mounted to said housing adjacent said exit end, the peripheries of said rollers abutting in a plane located centrally of said cavity, said first and second pairs of rollers having grooved-out portions around the peripheries thereof and said groovedout portions forming a passageway substantially aligned with said entrance and exit ends of corresponding crosssectional configuration to said workpiece; means secured to said housing cooperating with each of said rollers adjacent said housing wherein said means and said workpiece provide a substantially fluid-tight seal at said entrance and exit ends of said cavity; anode means substantially aligned with and adjacent to said entrance and exit ends resiliently biased to continuously contact said workpiece; apertured cathode means disposed within said cavity adapted for passage of said workpiece therethrough without physical contact; electrolyte supply means communicating with said cavity to provide a flow of electrolyte through said cavity and said apertured cathode means; and circuit means providing an electrical potential between said anode and cathode means.

2. Apparatus according to claim 1 wherein said first and second pairs of rollers are adapted for synchronized rotation.

3. A combination according toclaim 2 including torque-assist drive means operably connected to at least one of said rollers to maintain the rotational speed of said rollers correspondingly to the linear speed of said workplece.

4. Apparatus according to claim 1 wherein said anode means includes a pair of slidable electrical contactors disposed at said entrance and exit ends, the slidable contacting portions thereof shaped according to the configuration of said workpiece, and wherein cooling means are attached to said contactors in a heat transfer relationship.

5. Apparatus according to claim 1 wherein said apertured cathode means includes a first and second cathode having apertures corresponding to the cross-section of said workpiece substantially axially aligned within said longitudinal cavity and said entrance and exit ends whereby said workpiece when passing through said cavity passes through said first electrode and then said second electrode prior to exiting said cavity.

6. Apparatus according to claim 5 wherein said electrolyte supply means communicates with said cavity intermediate said first and second apertured cathodes providing the flow of said electrolyte to said cavity intermediate said electrodes and said supply means includes outlet means communicating with said cavity disposed on opposite ends of said annular electrodes as said supply means whereby the flow of electrolyte through said cavity and said apertured cathode is from the center of said cavity toward the entrance and exit ends of said cavity.

References Cited UNITED STATES PATENTS 1,191,386 7/1916 Battle 204206 XR 1,982,009 11/1934 McKinney et a1. 204272 2,384,660 9/1945 Ward 204206 2,764,540 9/1956 Farin et al 204272 XR 2,970,950 2/ 1961 Bahmann 204272 XR 3,324,022 6/1967 Keeleric 204143 XR 2,737,488 3/1956 Gray 204206 JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner US. Cl. X.R. 

